Effects of warming and nutrients on sediment community respiration in shallow lakes: an outdoor mesocosm experiment

Summary 1. Climate warming is expected to change respiration in shallow lakes but to an extent that depends on nutrient state. 2. We measured sediment respiration (SR) over the season in the dark on intact sediment cores taken from a series of flow-through, heated and unheated, nutrient-enriched and unenriched mesocosms. The natural seasonal temperature cycle ranged from 2 to 20 °C in the unheated mesocosms. In the heated mesocosms, the temperature was raised 4–6 °C above ambient temperatures, depending on season, following the A2 climate change scenario downscaled to the local position of the mesocosms, but enlarged by 50%. We further measured ecosystem respiration (ER) in the mesocosms based on semi-continuous oxygen measurements. 3. SR changed over the season and was approximately ten times higher in summer than in winter. SR showed no clear response to warming in the nutrient-enriched treatment, while it increased with warming in the unenriched mesocosms which also had lower fish densities. 4. ER was not affected by artificial warming or nutrient enrichment, but it was ten times higher in summer than in winter. 5. SR contributed 24–32% to ER. The SR:ER ratio was generally stimulated by warming and was higher in winter than in summer, especially in the nutrient-enriched mesocosms. 6. Our results indicate that climate warming may lead to higher SR, especially in clear, macrophyte-dominated systems. Moreover, the contribution of SR to ER will increase with higher temperatures, but decrease as the winters get shorter.

[1]  J. Kalff,et al.  Organic matter mineralization rates in sediments: A within‐ and among‐lake study , 1998 .

[2]  Daniel E. Schindler,et al.  CLIMATE CHANGE UNCOUPLES TROPHIC INTERACTIONS IN AN AQUATIC ECOSYSTEM , 2004 .

[3]  Brian Kronvang,et al.  Climate change effects on runoff, catchment phosphorus loading and lake ecological state, and potential adaptations. , 2009, Journal of environmental quality.

[4]  A. E. Greenberg,et al.  Standard methods for the examination of water and wastewater : supplement to the sixteenth edition , 1988 .

[5]  M. Pace,et al.  Respiration in lakes , 2005 .

[6]  K. Christoffersen,et al.  Measurements of chlorophyll-a from phytoplankton using ethanol as extraction solvent , 1987, Archiv für Hydrobiologie.

[7]  E. Jeppesen,et al.  Response of submerged macrophytes in Danish lakes to nutrient loading reductions and biomanipulation , 2003, Hydrobiologia.

[8]  D. Bouldin.  Models for Describing the Diffusion of Oxygen and Other Mobile Constituents Across the Mud-Water Interface , 1968 .

[9]  K. Sand‐Jensen,et al.  Net Heterotrophy in Small Danish Lakes: A Widespread Feature Over Gradients in Trophic Status and Land Cover , 2009, Ecosystems.

[10]  J. Sharp,et al.  Determination of total dissolved nitrogen in natural waters1 , 1980 .

[11]  M. Erlandsen,et al.  Modelling the Community Oxygen Production in Lowland Streams Dominated by Submerged Macrophytes1 , 1983 .

[12]  S. Carpenter,et al.  Assessing pelagic and benthic metabolism using free water measurements , 2007 .

[13]  P. Williams,et al.  Respiration in aquatic ecosystems. , 2005 .

[14]  L. Tranvik,et al.  Contribution of Sediment Respiration to Summer CO2 Emission from Low Productive Boreal and Subarctic Lakes , 2005, Microbial Ecology.

[15]  Manfred Ehrhardt,et al.  Methods of seawater analysis , 1999 .

[16]  Restoration of shallow lakes by nutrient control and biomanipulation—the successful strategy varies with lake size and climate , 2007 .

[17]  L. Carvalho,et al.  Interaction of Climate Change and Eutrophication , 2010 .

[18]  M. Piehler,et al.  Warming and Resource Availability Shift Food Web Structure and Metabolism , 2009, PLoS biology.

[19]  E. Eyto,et al.  Production and respiration of epilithic algal communities in irish lakes of different trophic status , 2003 .

[20]  E. Jeppesen,et al.  Temporal dynamics in epipelic, pelagic and epiphytic algal production in a clear and a turbid shallow lake , 2003 .

[21]  H. Odum.  Primary Production in Flowing Waters1 , 1956 .

[22]  M. Schallenberg,et al.  The ecology of sediment bacteria in lakes and comparisons with other aquatic ecosystems , 1993 .

[23]  W. Granéli,et al.  Sediment oxygen uptake in South Swedish lakes , 1978 .

[24]  David M. Lodge,et al.  From Greenland to green lakes : Cultural eutrophication and the loss of benthic pathways in lakes , 2003 .

[25]  Katherine Richardson,et al.  Global warming: Design of a flow‐through shallow lake mesocosm climate experiment , 2005 .

[26]  Corinne Le Quéré,et al.  Climate Change 2013: The Physical Science Basis , 2013 .

[27]  S. Juutinen,et al.  Sediment respiration and lake trophic state are important predictors of large CO2 evasion from small boreal lakes , 2006 .

[28]  J. Talling,et al.  Methods for physical and chemical analysis of fresh waters , 1980 .

[29]  R. Wetzel.  Limnology: Lake and River Ecosystems , 1975 .

[30]  Stephan Hülsmann,et al.  The impact of climate change on lakes in the Netherlands: a review , 2005, Aquatic Ecology.

[31]  J. Bennett,et al.  Reaeration in open-channel flow , 1972 .

[32]  M. Jansson,et al.  Pelagic and benthic net production of dissolved inorganic carbon in an unproductive subarctic lake , 2007 .